Q&A: Seth Lloyd

Q&A: Seth Lloyd

SL: Could the universe have arisen from total randomness? No. If we imagine that every elementary particle was a monkey typing since time began at the maximum speed allowed by the laws of physics, the longest stretch of Hamlet that could have been generated is something like “To be or not to be, that is the – .” But imagine monkeys typing at computers that recognize the random gibberish as a program. Algorithmic information theory shows that there are short, random-looking programs that can cause a computer to write down all the laws of physics. So for the universe to be complex, you need random generation, and you need something to process that information according to a few simple rules: in other words, a quantum computer.

TR: More practically: how far are we from widely used, commercial applications of quantum computing?

SL: Today, the largest general-purpose quantum computer is only a dozen bits. So we’re at least a decade or two away. But we’ve already built quantum computers that simulate other quantum systems: you could call them quantum analog computers. These little machines can perform computations that would require an ordinary computer larger than the universe.

TR: What’s the next big thing that needs to be done in quantum computing?

SL: From the techno-geek, experimentalist point of view, it’s the pacification of the microscopic, quantum world. It’s the Wild West down there.

TR: Programming the Universe concludes with a personal note. You describe how your friend Heinz Pagels, a renowned physicist, fell to his death while hiking with you in Colorado. You find some consolation in your theory of universal quantum computation: “But we have not entirely lost him. While he lived, Heinz programmed his own piece of the universe. The resulting computation unfolds in us and around us …”

SL: Well, it’s pretty poor consolation when someone you love is dead. But it’s a truer consolation than the idea that one day you might meet him in heaven.